Net neutrality is back in court again–and this decision could undo federal regulations that protect the principle. On Friday, the Washington, D.C. Court of Appeals is holding a hearing on net neutrality–the idea that broadband providers like cable and mobile companies can’t favor one sort of content provider over another. Depending on the court’s opinion, the Federal Communication Commission’s (FCC) efforts to protect net neutrality could be dealt a significant setback.

According to the Washington Post’s Brian Fung, the ruling of the three judges overhearing the case could let large Internet providers give preferential bandwidth to certain services such as streaming video or music providers. NPR’s Alina Selyukh adds that the court is asking whether the FCC has the authority to reclassify broadband Internet as a telecommunications service rather than a less-regulated “information service provider.”

Most legal observers expect net neutrality to end up in the Supreme Court due to the importance of the issue; although free speech activists, most tech companies, and the FCC have come out firmly on the side of net neutrality, it is firmly opposed by many Internet service providers and many conservative lawmakers. If net neutrality were repealed, it is possible a company such as Spotify could sign a deal for preferential speed on mobile phones–leading in turn to new headaches for their rivals. For most content providers, the repeal of net neutrality could serve as a Pandora’s box and create significant new complications for them.